VSim for GaAs & Diamond Semiconductor Devices

VSimSD168x75VSim for GaAs, Sb, and Diamond Semiconductor Devices models and simulates semiconductor effects in GaAs and diamond structures, including electron drift due to applied external field, electron scattering in GaAs MESFETs, electron emission from diamond and GaAs surfaces, and metal Schottky contacts in diamond.
 
VSim Photocathode Beam model

VSim for GaAs, Sb, and Diamond Semiconductor Devices models and simulates electron transport, drift and diffusion in GaAs (gallium arsenide) and diamond semiconductor structures, using the Monte Carlo device simulation approach. Diffusion from scattering due to phonon interactions are taken into account. Easy-to-use VSim can simulate MESFETs and metal Schottky contacts.

For diamond structures, VSim for GaAs, Sb, and Diamond Semiconductor Devices models charge mobility, both hole and electron generation and transport. For electrons in diamond structures with energies higher than the band gap of diamond (5.47 eV at room temperature), VSim for GaAs, Sb, and Diamond Semiconductor Devices models charge mobility and allows exploration of how secondary electrons and holes are generated due to impact ionization inelastic scattering. Applications for diamond structure simulation might include charge amplification and electron guns.

For gallium arsenide, VSim for GaAs, Sb, and Diamond Semiconductor Devices models the low energy regime (device charge transport) where electrons are near minima of energy band valleys. VSim for GaAs. Sb, and Diamond Semiconductor Devices models an operating MESFET (metal–semiconductor field effect transistor) using electron transport based on the Monte Carlo method for handling scattering of electrons with phonons (acoustic and optical, both polar and non-polar), charge impurity scattering, and plasmon scattering.

 

Features

  • Drift-diffusion evolution of electrons in Gallium Arsenide at different applied fields to about 10 MV/m
  • Electron emission when the electrons reach a GaAs surface
  • Secondary electron and hole generation in diamond
  • Transport of free charge carriers in diamond due to drift in an applied external field and their diffusion due to different scattering processes (including phonon and charge impurity ones)
  • Potential barriers at diamond interfaces (with vacuum and metals (Schottky contacts)) including the transmission probability given by the quantum tunneling of electrons and over barrier transmission
  • Electron transmission across a diamond interface including dielectric or metal
  • Absorbing embedded boundaries applied to these materials
  • Electron and hole induced secondary electron generation
  • Emitting boundaries
  • Emission-reflection at material interfaces
  • General treatment of electron emission probability based on transfer matrix calculations
  • Partially transparent absorbers
  • Reflecting slab boundaries
  • Space charge limited (Child-Langmuir) emission
  • Thermionic emission (Richardson-Dushman)

Example Simulations Included

Textbook Examples
Real World Examples

Questions? Contact us

 

VSim Animation

Arrayed Waveguide Grating Simulated in Demultiplexing Mode

In this simulation, the fundamental mode is launched using a unidirectional wave launcher. Matching Absorbing Layers prevent reflections from simulation boundary. B_z is displayed in this visualization. The wave is coupled to the ring and next to the second waveguide.

Silicon Waveguide in Silica Cladding

Shown in the visualization are positive and negative contours (red and blue) of B_y. The clipped views with multiple contours of B_y are shown in the multicolored scenes. The unidirectionality of the mode launcher enables arbitrary placement of the wave source along the waveguide. Matched Absorbing Layers (MAL) reduce reflections at simulation boundaries.

 
Microring Resonator Simulation Setup and Visualization

The simulation geometry is set up in VSim using the graphical user interface. The visualization displays B_z. Matching Absorbing Layers prevent reflections from the simulation. The wave is coupled to the ring and next to the second waveguide. The fundamental mode is launched using a unidirectional wave launcher.

 
Colliding Laser Pulses Launch an Electron Beam into a Plasma Accelerator

This simulation visualization by Estelle Cormier-Michel of Tech-X was one of the 2011 U.S. Department of Energy's Scientific Discovery through Advanced Computing (SciDAC) program OASCR (for Office of Advanced Scientific Computing Research) award winners.

Laser-Wakefield Accelerators "Dream Beam"

All different incarnations of laser-wakefield accelerators. It shows the background electron density (surface) plus some high-energy particles (beam) as particles.

 
Magnetic Field

The electron density in a 2D simulation of the expansion of a two-component plasma (electrons, ions, at same temperature) in an ambient magnetic field (out of plane). It initially expands symmetrically, but due to the charge separation (on average faster electrons than ions), the electrons get pulled back into the center, leading to some radial oscillations. The ambient magnetic field causes the rotation.

That's a configuration as encountered e.g. after ignition of the target in an Inertial confinement Fusion experiment. This shows that the debris created in an ICF chamber could be confined by a strong magnetic field, thus protecting e.g. the optical inlets into the chamber.

Magnetron

A Magnetron simulation created using VSim.

 
Multipactor Comparison

The video shows a side-by-side comparison of the 2 secondary electron models and how the resonance zone of the realistic model is much wider than that of the simple model.

Photocathode Modeling

Photocathode simulation modeling performed with VSim. Animation created with POV-Ray.

 
TESLA Cavity

Different incarnations of the wakefields generated by the propagation of an electron beam in a TESLA cavity.

 

Plasma Sheath

ITER2x3sheath

Sheath potential on ITER ICRF antenna.

Sheath Plasma Current

This movie shows one of the 24 modules of the ITER RF antenna, immersed in plasma, with a sheath model. Left plot shows sheath potential and right plot shows Je plasma current.

 

Modeling ICRF Heating in Alcator C-Mod

Geometry Construction

This movie gives some detail on the construction of the geometry used to simulate Alcator C-Mod's field-aligned ICRF antenna in VSim. CAD files from the antenna (provided by MIT engineers) are imported to the VSim grid; thereafter, the antenna module is embedded in a half-torus rendering of C-Mod's vacuum vessel. Finally, an equilibrium plasma density profile (provided by MIT scientists) is loaded into the vessel.

Electric Field Contours

Vertical component of the electric field induced by the field-aligned ICRF antenna in the Alcator C-Mod device, in a simulation which imports plasma density and magnetic field profiles from experimental data. The geometry of the simulation is described in Modeling ICRF Heating in Alcator C-Mod: Geometry Construction. The phasing of the antenna straps is [0, π, 0, π]; complex patterns of fast wave propagation into and through the plasma core are clearly visible.

Plasma with Electric Field

Vertical component of the electric field induced by the field-aligned ICRF antenna in the Alcator C-Mod device, in a simulation which imports plasma density and magnetic field profiles from experimental data. In this animation the plasma profile is also shown; the data is the same as was used in Modeling ICRF Heating in Alcator C-Mod: Electric Field Contours, though the view is slightly different. The phasing of the antenna straps is [0, π, 0, π]; complex patterns of fast wave propagation into and through the plasma core are clearly visible.

Midplane Electric Field

Vertical component of the electric field induced by the field-aligned ICRF antenna in the Alcator C-Mod device, in a simulation which imports plasma density and magnetic field profiles from experimental data. In this animation the toroidal midplane of the device is shown; the data is the same as was used in Modeling ICRF Heating in Alcator C-Mod: Plasma with Electric Field, though the view is slightly different. The phasing of the antenna straps is [0, π, 0, π].

 
Poloidal Plane Electric Field

Vertical component of the electric field induced by the field-aligned ICRF antenna in the Alcator C-Mod device, in a simulation which imports plasma density and magnetic field profiles from experimental data. In this animation a two-dimensional poloidal cut across the antenna coax feeds is shown; the phasing of the antenna straps is [0, π, 0, π].

 

NIMROD

current3D

3D NIMROD simulation of the toroidal current density evolution based on an initial 2D reconstructed state from the DIII-D tokamak. This experimental discharge was characterized by an edge-localized mode free state with edge harmonic oscillations. See https://nimrodteam.org and https://fusion.gat.com/global/DIII-D for more information.

pressure3D

3D NIMROD simulation of the pressure evolution based on an initial 2D reconstructed state from the DIII-D tokamak. This experimental discharge was characterized by an edge-localized mode free state with edge harmonic oscillations. See https://nimrodteam.org and https://fusion.gat.com/global/DIII-D for more information.

 
VSim simulation of charge generation and transport in diamond
 
 
 
Charge generation and transport in diamond

Secondary electrons and holes generated due to impact ionization inelastic scattering.

 

 

VSim simulation of metal Schottky contacts in diamond

 
 
 
Metal Schottky contact in diamond

The interface between diamond and metal is modeled using a GridBoundary object, which is a very general boundary that can be curved and oriented in any direction. A pseudo-random distribution of electrons is introduced as an initial condition, with thermal velocities. A uniform electrostatic field sweeps the electrons to the right, where they encounter a barrier (before the Schottky contact).

 

 
VSim simulation of electron transport in GaAs
Electron transport in GaAs

Drift-diffusion evolution of electrons in gallium arsenide.

 

 

VSim simulation of electron transport and emission in diamond

 
 
Electron transport and emission in diamond

Electron transport in a gallium arsenide based (GaAs) semiconductor device using an electrostatic push algorithm to create an operating MESFET transistor.

 

 
VSim MESFET simulation
 
 
 
 
MESFET transistor (metal–semiconductor field effect transistor) using
electron transport in a gallium arsenide based semiconductor device
(GaAs)

An initial population of electrons is loaded at the source and drain. Electrons which impact the source or drain can be absorbed, electrons that hit elsewhere on the simulation boundary will be reflected back into the simulation (this includes the gate).

VSim simulation of charge generation and transport in GaAs

Charge generation and transport in GaAs

Electron transport in gallium arsenide due to drift in applied external field and modeling electron emission when the electrons reach the GaAs surface.

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VSim packages provide the pricing flexibility and convenience you want.  Choose the package or set of packages that has the physics simulation functionality that you need.

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Enables resolution of kinetic effects for discharges not observable in fluid simulations.  More...

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Large-scale simulations of laser-plasma and beam-plasma acceleration experiments.  More...

 

VSim packages provide you with a diverse range of relevant examples, macros and the powerful graphical user interface to the simulation engine, together with embedded analysis tools. Functionality is collected in common packages to provide the pricing flexibility and convenience you want. Custom packages are also available to give even more flexibility in pricing. See the VSim Features Matrix.

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